The estate comprises 5,000 acres (20 km2) of woodlands (known as Ashridge Forest), commons and chalk downland which supports a rich variety of wildlife. It also offers a good choice of waymarked walks through outstanding country. The estate is currently owned by the National Trust.

It should not be confused with Asheridge, which is a hamlet about five miles (8 km) south-west, the other side of Berkhamsted.

In 1848 the estate passed to the Earls Brownlow, another strand of the Egerton family,[5] and then in 1921 it was split, with the land passing to the National Trust, while the house and garden was acquired by speculators.[6]

In 1928 Urban Hanlon Broughton purchased the house as a gift for the Conservative Party intended to commemorate Andrew Bonar Law.[6] In July 1929 Ashridge opened as a College under the governance of the Bonar Law Memorial Trust (BLMT). The BLMT was charged by its Founding Deed to pursue the following goals, namely

(a) honouring the memory of a great statesman, (b) the preservation of the house and grounds as an historic building, (c) to create an educational centre … (d) to train lecturers, speakers and writers to further the study of the subjects outlined above (e) … provide lectures and/or discussions on these subjects open to the public or for those who had paid fees to attend, (f) … provide a supporting staff, (g) to allow boarding by those attending the lectures and discussions.[7]

For the next fifteen years the college, the full title of which was the Bonar Law Memorial College, Ashridge was to act as a school for Conservative intellectuals creating, in their own words, ‘Conservative Fabians’, and as a ‘College of Citizenship’ for ‘the general education of the electorate’ . In 1954 its Deed of Foundation was changed by Act of Parliament, and Ashridge was ‘re-founded’ as an educational charity. In 1959 it became a Management College, which it remains today.[8]

In 1959 Ashridge College was re-launched to provide management training, and was named Ashridge Business School.[9] In 2015, Ashridge Business School operationally merged with Hult International Business School, an American business school with campuses in seven cities around the world. As part of the merger, Ashridge Business School changed its name to Ashridge Executive Education.[10]

Ashridge house was built on the site of the 13th-Century priory building which had been demolished in 1800. Some parts of the old priory were incorporated into the house by James Wyatt, including the undercroft of the monastic refectory, featuring two aisles, seven bays and a rib-vaulted ceiling, which he repurposed as a beer cellar below the dining room and drawing room.[15]

The mansion is built of ashlar faced with Totternhoe stone with a castellatedparapet and low-pitched slate roofs. It features a variety of casement windows including pointed arch and ogee lights typical of the early Gothic Revival style. Before his untimely death, James Wyatt completed the north-facing front entrance and the central block, containing the state apartments and western courtyards. Jeffry Wyatt added private apartment blocks at an angle to the main building and an orangery with a turret in 1815–17. The main entrance features a projecting porte-cochère and octagonal turrets, added by Jeffry Wyatt c.1814.[15]

The house incorporates a Gothic Revival Chapel designed by James Wyatt, completed by Jeffry Wyatt in 1817. The most notable exterior feature of the chapel is its spire which was demolished in 1922 by Lord Brownlow as it had become structurally unsound. The spire which can be seen today is in fact a fibreglass replica which was erected in 1969. The chapel interior features a pair of Fourteenth-Century carved doors, fan-vaulted coving supporting a canted panelled ceiling; a set of carved oakchoir stalls designed by Jeffry; and an array of Rayonnantlancet windows.[13] The windows were originally fitted with stained glass panels depicting scenes from the Bible; the glass was imported by the 7th Earl from Germany, having been originally designed in the Sixteenth Century for Steinfeld Abbey and Mariawald Abbey. The glass was auctioned off at Sotheby's in 1928 and acquired by the Victoria and Albert Museum.[16] One glass panel featuring the Blessed Virgin was placed in the nearby Church of Ss Peter and Paul at Little Gaddesden; another, depicting St Peter was in Christ Church, Croydon in London. Beneath the chapel is a vaulted medieval wellhouse with a 224-foot (68 m) well.[15]

Outside the house stands the timber-frame and brick Fourteenth-Century Monks' Barn in the Monks' Garden. It was remodelled in 1816 by Jeffry Wyatt who added a covered walkway. In 1884 Mathew Digby Wyatt added the red brick Fern House.[15]

The house is used as a management training college and is not normally open to the public, although special tours are offered during the summer.[19]

Berthezène, Clarisse (2015). Training minds for the war of ideas. Ashridge College, the Conservative Party and the cultural politics of Britain, 1929-54. Manchester: Manchester University Press. ISBN978-0-7190-8649-6.